Raft of optimiser changes

Sergei Trofimovich slyich at gmail.com
Sat Aug 30 10:38:32 UTC 2014

On Thu, 28 Aug 2014 11:16:03 +0000
Simon Peyton Jones <simonpj at microsoft.com> wrote:

> I've just pushed a bunch of Core-to-Core optimisation changes that have been sitting in my tree for ages.  The aggregate effect on nofib is very modest, but they are mostly aimed at corner cases, and consolidation.
>         Program           Size    Allocs   Runtime   Elapsed  TotalMem
>             Min          -7.2%     -3.1%     -7.8%     -7.8%    -14.8%
>             Max          +5.6%     +1.3%    +20.0%    +19.7%    +50.0%
> Geometric Mean          -0.3%     -0.1%     +1.7%     +1.7%     +0.2%
> The runtime increases are spurious - I checked.
> A couple of perf/compiler tests (i.e. GHC's own performance) improve significantly, which is a good sign.
> I have a few more to come but wanted to get this lot out of my hair.

Hello Simon!

The compiler improvements look great!

Although running 'fulltest' one test caught core lint error:
>    typecheck/should_compile  T7891 [exit code non-0] (hpc,optasm,profasm,optllvm)

It can be reran as:
    $ make fulltest THREADS=12 TEST=T7891

The result of optasm run:

=====> T7891(optasm) 3365 of 4096 [0, 0, 0] 
cd ./typecheck/should_compile && '/home/slyfox/dev/git/ghc-validate/inplace/bin/ghc-stage2' -fforce-recomp -dcore-lint -dcmm-lint -dno-debug-output -no-user-package-db -rtsopts -fno-ghci-history -c T7891.hs -O -fasm  -fno-warn-incomplete-patterns >T7891.comp.stderr 2>&1
Compile failed (status 256) errors were:
*** Core Lint errors : in result of Simplifier ***
<no location info>: Warning:
    In the type ‘a_12 -> t_aiE -> t_aiE’
    @ a_12 is out of scope

(attached it's complete output)

Thank you!


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